Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making electrical device
Reexamination Certificate
1999-03-02
2001-05-01
Duda, Kathleen (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making electrical device
C430S329000, C134S001000
Reexamination Certificate
active
06225030
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a post-ashing treating method for substrates. More particularly, the invention relates to a post-ashing treating method for substrates which exhibits an excellent performance in treating substrates having been dry-etched under strict conditions followed by ashing and also exerts favorable corrosion-inhibiting effects on various metallic wires and metallic layers. The present invention is appropriately applicable to the production of semiconductor devices such as Ics and LSIs as well as liquid-crystal panel devices.
2. Description of Relevant Art
Semiconductor devices such as ICs and LSIs as well as liquid-crystal panel devices are fabricated by a process comprising the following steps: forming a conductive metallic layer or an insulating layer such as an SiO
2
film formed onto a substrate by chemical vapor deposition or other suitable techniques; applying a uniform photoresist layer over the metallic or insulating layer; selectively exposing the applied photoresist layer to light and developing the exposed layer to form a photoresist pattern; selectively etching the above-mentioned conductive metallic layer or insulating layer through the photoresist pattern as a mask pattern to form a fineline circuit; and stripping away the unwanted photoresist layer.
As the metallic layer, use may be made of various ones, for example, aluminum (Al), an aluminum alloy (Al alloy) such as aluminum-silicon (Al—Si), aluminum-copper (Al—Cu) or aluminum-silicon-copper (Al—Si—Cu); pure titanium (Ti); or a titanium alloy (Ti alloy) such as titanium nitride (TiN) or a titanium-tungsten system (TiW). One or more of such metallic layers are formed onto the substrate.
With the recent tendency toward high-density integrated circuits, dry etching enabling fine etching with a higher density has become the major means. Also, it has been a practice to employ plasma ashing, etc. to remove the unwanted photoresist layers after etching.
After the completion of these strict processing, resist residues such as modified photoresist films would adhere and remain in the side or bottom of patterns. It is also observed that metal depositions are formed in the step of etching metallic layers. It is, therefore, necessary to completely remove these residues, as there arises some problems, for example, a decrease in the yield of producing semiconductors.
These residues differ in composition from one another depending on the type of the etching gas employed, the ashing conditions, the type of the metallic layer(s) formed on the substrate, the type of the photoresist employed, etc. In recent years, attempts have been made to improve semiconductors by various methods. As a result, the treating conditions in each step become strict and a great variety of metals are employed therefor. Consequently, the residues and depositions become complicated, which make it difficult to identify the those compositions. Under these circumstances, no satisfactory treating liquid has been known so far. Among all, it is very difficult to completely remove residues of photoresists to which inorganic natures have been imparted by plasma gases.
As liquid compositions for treating these residues, Unexamined Published Japanese Patent Application No. 222,574/1996 has disclosed detergent compositions which comprise alcohols and quaternary ammonium hydroxides. Although these compositions can exert treating performance at a certain extent, there arises another problem that metallic layers are corroded away thereby.
The present inventors conducted intensive studies with a view to solving the above-mentioned problems. As a result, they found that these problems could be solved by treating substrates with treating liquid compositions containing lower alkyl quaternary ammonium salts, polyhydric alcohols and water in specified proportions. The present invention has been accomplished on the basis of this finding.
SUMMARY OF THE INVENTION
An object, therefore, of the present invention is to provide a post-ashing treating method for substrates which exhibits, in treating substrates provided with metallic layers having been dry-etched under strict conditions followed by ashing, excellent effects of removing resist residues such as modified photoresist films and metal depositions and also exerts favorable corrosion-inhibiting effects on the substrates.
Accordingly, the present invention relates to a post-ashing treating method for substrates comprising the following steps:
(I) forming a photoresist layer on a substrate having metallic layer(s) thereon;
(II) selectively exposing the photoresist layer to light;
(III) developing the light-exposed photoresist layer to provide a photoresist pattern;
(IV) etching the substrate through the photoresist pattern as a mask pattern to form a metallic wired pattern;
(V) ashing the photoresist pattern; and
(VI) after the completion of the ashing, bringing the substrate into contact with a treating liquid composition to thereby treat the substrate;
characterized in that the treating liquid composition employed above is one which comprises: (a) 0.5-10 wt % of a lower alkyl quaternary ammonium salt; (b) 1-50 wt % of a polyhydric alcohol; and (c) water as the balance.
DETAILED DESCRIPTION OF THE INVENTION
Now, the post-ashing treating method for substrates according to the present invention will be described in detail.
In the method of the present invention, use is made of treating liquid compositions comprising: (a) 0.5-10 wt % of lower alkyl quaternary ammonium salts; (b) 1-50 wt % of polyhydric alcohols; and (c) water as the balance.
The term “lower alkyl” as used in component (a) means alkyl groups having 1 to 6 carbon atoms. Particular examples of the lower alkyl quaternary ammonium salts include tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, trimethylethylammonium hydroxide, (2-hydroxyethyl)trimethylammonium hydroxide (i.e., choline), (2-hydroxyethyl)triethylammonium hydroxide, (2-hydroxyethyl)tripropylammonium hydroxide and (1-hydroxypropyl)trimethylammonium hydroxide. Among all, it is preferable to use TMAH, choline, etc. These lower alkyl quaternary ammonium salts may be used either independently or in combination with themselves.
As component (b), it is preferable to use one or more members selected from the group consisting of glycerol, ethylene glycol, propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol and 2,3-butylene glycol. Among all, glycerol is particularly preferred. These polyhydric alcohols may be used either independently or in combination with themselves.
Water is used as component (c).
The treating liquid compositions to be used in the present invention contain components (a) to (c) in the following proportions: 0.5-10 wt %, preferably 1-5 wt %, of component (a); 1-50 wt %, preferably 3-40 wt %, of component (b); and component (c) as the balance.
The proportion of each component is particularly important in the present invention. When component (a) is used in excess or component (b) is used in short, no sufficient corrosion-inhibiting is ensured. When component (b) is used in excess or component (a) is used in short, on the other hand, the ability to remove residues is deteriorated.
When the method of the present invention is employed in a dip treatment or a shower treatment wherein a substrate is brought into contact with a treating liquid composition for a long time (i.e., 5 to 20 min), it is preferable that the composition contains component (b) in a relatively large amount, i.e., 25-50 wt %, still preferably 30 to 45 wt %. In a paddle treatment wherein the contact is completed within a short period time (i.e., 30 sec to 1 min), it is preferable that component (b) is used in a relatively small amount, i.e., 1-25 wt %, still preferably 3-20 wt %.
These treating liquid compositions may further contain water-soluble organic solvents, surfactants, etc., so long as the effects of the present invention are not deteriorated thereby.
Examples of the water-soluble organic so
Kobayashi Masakazu
Nakayama Toshimasa
Tanabe Masahito
Wakiya Kazumasa
Duda Kathleen
Tokyo Ohka Kogyo Co. Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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